WASHINGTON (AP) _ The Senate approved tougher pipeline safety provisions Friday and reached agreement on measures that would sharply increase the use of ethanol in gasoline, while phasing out an additive blamed for water pollution.

The pipeline safety measure, approved by a 94-0 vote, was inserted into a sweeping energy bill being debated by the Senate. Similar pipeline measures cleared the Senate in each of the past two years, but never made it through the House.

Separately, senators announced agreement on a measure that would triple the amount of ethanol produced for gasoline to 5 billion gallons and ban MTBE, the gas additive blamed for fouling waterways in many states.

The agreement would phase out MTBE over four years and require at least 5 billion gallons of corn-based ethanol be used by refiners by 2012. It also would end the federal mandate that that gasoline contain a certain amount of oxygenate in areas with clean air problems.

The agreement had been worked out over several weeks in negotiations among farm interests, the oil industry, environmentalists and MTBE manufacturers. Most of the provisions are already in the bill, but the compromise assured they would not be stripped from the legislation.

Senate Majority Leader Tom Daschle, D-S.D., called it ``a fine balance of often disparate and competing interests'' that will provide refiners with greater flexibility in federal gasoline regulations while continuing to protect air quality.

But Sen. Dianne Feinstein, D-Calif., said the ethanol requirements may cause gasoline shortages in California as the state replaces MTBE. ``This could have a very detrimental impact on California, leaving the state open to gasoline price spikes and shortages,'' said Feinstein in a statement.

Ethanol industry spokesmen said under the mandate, California refiners could choose to use ethanol or purchase credits from other refiners in other parts or the country.

Senate approval of the pipeline measures were spurred by concern over several major pipeline accidents including a fiery one in 1999 in Bellingham, Wash., where three young people were killed, and a pipeline explosion in 2000 in New Mexico that killed 12 campers.

The amendment calls for better training of federal and state pipeline inspectors, and expansion of pipeline monitoring and reporting by industry. Also, it would authorize more research into ways to make safer the nation's more than 1.6 million miles natural gas and other fuel pipelines run by 3,000 operators.

In response to security concerns, raised by the Sept. 11 terrorist attacks, the Senate added provisions to bar the release of some sensitive pipeline data that in the past had been readily available.

``Sensitive information must not be released into the wrong hands,'' said Sen. John McCain, R-Ariz., one of the measures' lead sponsors. He noted the Senate in 2000 and again last year passed similar pipeline safety legislation, but each time the House failed to act.

Meanwhile, there were signs that Republican support for drilling in Alaska's Arctic National Wildlife Refuge will erode if the controversy threatens Senate passage of the broader energy legislation, say some lawmakers.

While supporters of such drilling may be able to muster a narrow majority, they have been unable to get close to the 60 votes needed to overcome a certain filibuster by Democrats who have vowed to protect the refuge.

Along with a largely Democratic proposal to require automakers to significantly improve fuel economy, drilling in ANWR, as the refuge is known, is by far the most contentious issue facing senators as they try to craft legislation to direct the nation's energy policy.

Both issues are expected to come to a head late next week while the Senate for now focuses on less divisive parts of the bill.

Sen. Frank Murkowski, R-Alaska, who has led the pro-drilling forces, signaled his frustration Thursday when he vowed to launch his own filibuster against the energy bill if opponents prevent him from offering an amendment to open the refuge to oil companies.

``We can talk and talk and talk,'' warned Murkowski, promising to use parliamentary procedures to tie up the entire legislation if necessary.

Such an impasse could force Daschle to withdraw the bill, senators acknowledge.

``If he (Murkowski) wants to stop an energy bill for the nation because he can't get ANWR, so be it,'' said Sen. John Kerry, D-Mass. Kerry is among Democrats who promise to filibuster any drilling proposal.

President Bush favors drilling in ANWR, arguing that it is necessary to meet rising U.S. energy demands and that it can be carried out without harming the refuge's delicate ecosystem.

But a growing number of Republicans acknowledge that ANWR's oil may be too big a price to pay if it means abandoning altogether a bill that has other valuable, hard-fought provisions.

In addition to the ethanol-MTBE provisions, which has widespread support from powerful interest groups, and the pipeline safety measures, the bill also would provide incentives to spur construction of a natural gas pipeline in Alaska and assures the nuclear industry continues to have a cap on liability from a major nuclear accident.

These all are measures that have broad support and would fall victims to the impasse over the Arctic refuge.

Asked Thursday if an energy bill without ANWR drilling might be acceptable, Minority Leader Trent Lott, R-Miss., replied: ``There are many areas that are important in this bill. ... It's not just about drilling there, but you'll have to look at the whole picture.''